In the field of optical communications, it may be desirable to amplify optical signals that are being generated and transmitted to increase output signal power and/or to compensate for various losses due to optical components, (e.g., coupling losses). Traditionally, this has been done by converting the optical signal into an electrical signal, amplifying the electrical signal, and then converting it back to an optical signal. This is an inefficient process and requires a number of additional components. In response to the need for direct optical amplification, optical amplifiers such as semiconductor optical amplifiers (SOAs) and Erbium doped fiber amplifiers (EDFAs) have been developed. An optical amplifier is an element that has an optical amplification medium, which is able to amplify an optical signal directly without first converting it to an electrical signal. SOAs have the additional advantage of being very compact and thus may be included within a transmitter package. Therefore, SOAs have become an important part of integrated optical devices and have allowed the integration of many optical components into smaller form factor packages.
In a direct amplifying application, it may be desirable for an SOA to be optically coupled directly to a semiconductor laser, and for both components to be housed in a single package. The addition of an electrical lead to provide operational power to the SOA, however, may lead to packaging difficulties. In many applications this is undesirable and an additional DC lead to operate an SOA is not provided in commonly used standard packages, such as the industry standard 7-PIN electro-absorption modulated laser (EML) package. The higher optical output power of these devices are desirable, but no pins are available for the additional power connections. Any changes to the package are undesirable due to compatibility considerations in pre-existing optical communications systems. Even if an additional DC lead were provided, the inclusion of an additional power supply to drive the SOA raises further compatibility issues within pre-existing optical communications systems that have only a single supply available to generate the optical signal. Therefore, the inclusion of SOAs within such standard packages has been problematic.